In recent years, due to depletion of energy, the development of an environmentally-friendly vehicle as an alternative transportation means is in increasingly active progress. Examples of representative environmentally-friendly vehicles include hybrid vehicles, electric vehicles, hydrogen fuel cell electric vehicles and the like. Since such an environmentally-friendly vehicle does not adopt a method of operating an engine, it does not generate an engine noise or the like while driving unlike an existing internal combustion engine vehicle. Accordingly, the establishment of regulations on the environmentally-friendly vehicles is being prepared to protect pedestrians around a vehicle, and the research and development of a virtually operating sound generation system of an environmentally-friendly vehicle are required in relation to the establishment of regulations.
That is, an environmentally-friendly vehicle such as a hybrid vehicle, an electric vehicle, a hydrogen fuel cell electric vehicle or the like does not generate an engine's unique sound generated from a gasoline vehicle or a diesel vehicle. For this reason, there occur problems in that an accident may occur since a pedestrian does not recognize a vehicle approaching the pedestrian or a vehicle at a place such as an alley or an indoor parking lot, and in that it is also difficult for a driver to recognize the startup state or the current state of a vehicle since a vehicle noise is not generated.
Furthermore, a vehicle including an energy recharge system, such as an electric vehicle, a hydrogen fuel cell electric vehicle or the like, entails problems in that it is difficult to know whether the recharge is started or finished upon the recharge by the connection of a charger, and in that it is very inconvenient to use the vehicle due to extreme insufficiency of vehicle information that can be recognized by a driver in relation to a risk caused by discharge of a battery or deficiency of fuel.
In an attempt to solve such problems, apparatuses for generating a virtual engine sound for environmentally-friendly vehicles are recently developed. However, virtual engine sound generation apparatuses that are being currently developed simply generate a sound similar to an engine sound associated with the driving of a vehicle and cannot provide various functions to a pedestrian or a driver, and its technical level is still insignificant since information on the current state of the vehicle is provided insufficiently.
In Particular, although the engine of a vehicle starts, the startup state of the engine cannot be identified since an engine startup sound unique to the vehicle is not generated. In addition, since only a message informing that the vehicle can travel is simply displayed on the cluster of the vehicle, it is insufficient for the transmission of the current vehicle state to the driver. Further, although an environmentally-friendly vehicle includes an apparatus for generating a virtual engine sound, currently, the apparatus merely generates a sound similar to a sound of a vehicle according to the speed of the vehicle and informs a pedestrian of approach of the vehicle by increasing or decreasing the volume when the vehicle travels in a specific speed section. However, such a conventional apparatus encounters a problem in that the driver and the pedestrian may feel uncomfortable since the actual behavior of the driver accelerating or decelerating the vehicle somewhat does not match with the generated virtual engine sound of the vehicle. In addition, there is also a problem in that since the driver who is a subject of driving the vehicle is not informed of the current state of the vehicle, he or she cannot properly grasp the current state of the vehicle.
Besides, such a conventional technology controls only the volume of a sound, and, furthermore, it is difficult to confirm whether or not a normal sound source is output through a general self-diagnosis on the volume control.
As an example of the prior art, there has been disclosed Korean Patent Registration No. 10-985767.